$ { \left[\begin{array}{rr}{3} & {2} \\ {3} & {1} \\ {3} & {1}\end{array}\right]+\left[\begin{array}{rr}{-1} & {-2} \\ {-1} & {4} \\ {3} & {4}\end{array}\right] = {?} } $
Explanation: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{3}+{-1} & {2}+{-2} \\ {3}+{-1} & {1}+{4} \\ {3}+{3} & {1}+{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{2} & {0} \\ {2} & {5} \\ {6} & {5}\end{array}\right]}$